Trickle Chargers - What are your thoughts or recommendations? - PeachParts Mercedes-Benz Forum

DC Josh · #1 05-04-2013, 09:06 PM

My '84 300d is not my primary mode of transport. Since I am working on it, I do not often have the engine running at constant intervals or for extended periods. I don't want the battery to drain on me and I was thinking of getting one of those 5w solar deals to hook into the cigarette lighter.

Has anyone else used this method? What is the brand you used and what was the wattage?

Thanks!

- DC Josh

pawoSD · #2 05-04-2013, 09:50 PM

Won't work, cigarette outlet is off/disconnected when the car is off. You'd need to wire the plug to always be live, or directly connect the solar panel to the battery. If connected, yes, the 5W panel will me more than enough to keep it topped off. All that uses power when the car is off is the radio memory and analog clock....virtually nothing.

Whiskeydan · #3 05-04-2013, 09:51 PM

Just disconnect the negative side and you should be fine.

dude99 · #4 05-04-2013, 09:55 PM

You could wire in a circuit direct to the battery and hide the connector somewhere under one of the kick panels so you'd never see it...

vstech · #5 05-05-2013, 09:25 AM

5w panels only put that out in direct sunlight. inside the car, you are only getting like 1 watt... that's 1/12 of an amp... even the ultra cheapo trickle chargers put out 1.5 amps... it's going to take a month to recharge one glow/start session...
the 15 watt panels get close to an amp and they STILL don't handle the recharging of the battery on these cars...
those 5 watt panels are for connecting to a standby battery under good conditions...
I've got TWO 45w panel sets connected that's 7amps... and it does a fair job of maintaining my batteries...

Graplr · #6 05-05-2013, 09:33 AM

Agree with vstech, don't waste your time on the small solar chargers, they won't accomplish what you want. Disconnecting the battery will likely be your simplest option. Or youcould buy a cheap trickle charger that pkugs into the wall.

lorainfurniture · #7 05-05-2013, 09:41 AM

Some of my cars sit for 6+ months between starts. You should do a parasitic draw test to see what is killing your battery.

Any healthy car and battery should last a minimum of 6 months.

ytmtnman · #8 05-05-2013, 09:45 AM

Quote:

Originally Posted by lorainfurniture

Some of my cars sit for 6+ months between starts. You should do a parasitic draw test to see what is killing your battery.

Any healthy car and battery should last a minimum of 6 months.

A bad battery can behave this way too.

lorainfurniture · #9 05-05-2013, 11:12 AM

Exactly. A healthy car AND battery.

cornemuse · #10 05-05-2013, 12:07 PM

I got a junker 300d a few years ago & put a HF $4.99 on sale trickle charger on the batt (in the garage). The batt in my 300cd went out & I put in the stored batt, (after 2 + years of storage), works perfectly (adter another 2 + years). "Something good from Harbor Freight"

-c-

compu_85 · #11 05-05-2013, 01:08 PM

Quote:

Originally Posted by Graplr

Agree with vstech, don't waste your time on the small solar chargers, they won't accomplish what you want.

I disagree. With yee olde cars that don't draw a lot of juice with the key off, I've found that a reasonable quality solar charger will keep the battery topped up. I leave a good quality one in my F350 that is rarely driven now, and it is able to keep both batteries full.

Of course the suggestions for checking the parked draw and condition of the battery are good ones.

-J

jay_bob · #12 05-05-2013, 02:05 PM

I have to agree with Compu85 on this one. The resting drain of a properly functioning 123 with a healthy battery is negligible, on the order of a few tens of mA to keep the clock turning. Add a few tens of mA to keep the memory held in the stereo.

There should be nothing else drawing on a properly functioning 123. In that case a small 5 W charger should be plenty to overcome the draw and the self discharge.

Newer cars, even the 124s, probably have a higher resting draw due to the electronics, particularly second gen 124s with the convenience control module.

Higher capacity may in fact hurt the battery if there is not a regulator to limit the charge.

vstech · #13 05-06-2013, 10:28 AM

really? 5 watts? INSIDE a car? likely only getting 1 watt... is enough to charge a 123?

enough to keep a battery that's charged topped off, sure, but enough to maintain a occasionally driven very short trips diesel battery? I don't know.

and, most trickle chargers are unregulated at 1.5 or 2 amps... 15 watts of 14v power is ... 1.1 amps? 45 watts is 3 amps at PEAK sunlight... I have a charge controller on my multi panel setup to float the batteries at 13.8v, but I doubt it is needed on a 15 watt panel.

pawoSD · #14 05-06-2013, 11:48 AM

I would imagine they might want the solar charger because the car sits somewhere where an outlet is not convenient or practical.....

DC Josh · #15 05-06-2013, 01:05 PM

Quote:

Originally Posted by pawoSD

I would imagine they might want the solar charger because the car sits somewhere where an outlet is not convenient or practical.....

Thanks for all of the inputs from everyones experiences. pawoSD hit the nail on the head. I don't have the space or outlet for a dedicated trickle charger.

The one that I am looking at is a 5W charger with a built in charge controller (I like the piece of mind). The car sits in direct south facing sunlight so I know it will be getting a good amount of light to keep the battery topped off.

Thanks again, it looks like I will set something up to run a wire directly to the battery.

- DC Josh